Soil into concrete

A fascinating Guardian articlefrom its ‘Overstretched Cities Series’ on urbanisation, as population pressure on the planet continues in the least economically developed parts of the wo rld:

What happens to those cities over the next 30 years will determine the global environment and the quality of life of the world’s projected 11 billion people. It’s impossible to know how exactly how cities will grow, of course. But the stark fact, according to the United Nations, is that much of humanity is young, fertile and increasingly urban. The median age of Nigeria is just 18, and under 20 across all Africa’s 54 countries; the fertility rate of the continent’s 500 million women is 4.4 births. Elsewhere, half of India’s population is under age 25, and Latin America’s average age is as high as 29.